COVID-19 Vaccination in Medically Complex Adults

It’s a constant challenge: Immunizers in pharmacies everywhere need updated guidance on vaccine timing and platform selection (messenger RNA [mRNA] vs protein-based vaccines) when medically complex adult patients request COVID-19 vaccines. Just as it is recommended that they receive the annual influenza vaccination, most adults younger than 65 years who are not immunocompromised should receive 1 dose of the updated COVID-19 vaccine each season.^1,2 Adults 65 years and older are advised to receive a second dose 6 months later to maintain protection.¹ Additional considerations apply for patients who are immunocompromised, pregnant, or lactating, or who have a history of myocarditis or pericarditis or prior anaphylaxis.^2-5 Most of these patients can be vaccinated.^3-5 But the more difficult questions are: Which vaccine? And when?

Obtain a Focused Medical History

Before vaccinating any patient, pharmacy staff need to identify any underlying conditions, diagnoses, and their current health status. It is critical to identify patients who qualify as medically complex. Clues include medications that may affect vaccine response or safety (eg, immunosuppressants, biologics, and chemotherapy) and self-reported transplant, active chemotherapy, or biologic therapy. This is also the time to ask about allergies or anaphylaxis to anything, including vaccines.⁶ If the patient reports a vaccine allergy, asking them to specify which vaccine can help identify the component or platform.⁶

Assess Vaccination History

Access to the patient’s vaccination records can make this step simple. Pharmacy staff should identify prior COVID-19 vaccination dates, products, and number of doses received. If centralized data are unavailable, pharmacy staff will need to rely on patient self-report; if so, they should encourage patients to start carrying a paper or electronic vaccination record (and the staff should provide one).

Asking patients whether they tolerated past doses with or without significant adverse effects can guide the selection of the next product.⁷ Patients who have experienced severe allergic reactions, myocarditis, pericarditis, or other serious vaccine-related adverse events may require additional evaluation and, in some cases, referral to a specialist.⁵ Developing a shared vaccination plan entails collaborating with the patient and, when appropriate, other health care providers to determine whether vaccination should proceed, be deferred, or requires additional evaluation.

Identify Factors That May Influence Vaccine Timing

Then, immunizers need to discuss recent infections, transplantation, chemotherapy, immunosuppressive therapy, pregnancy status, and/or recent cardiac inflammation.³ If any of these conditions are present, reference current CDC and specialty society recommendations regarding optimal timing. The Table^3-5,8 describes issues of concern in medically complex patients.

Select the Most Appropriate Vaccine Product

Based on the patient's clinical circumstances and history, selecting a platform is the next step. COVID-19 vaccines are available as mRNA vaccines or protein-based vaccines.⁷ Most patients can receive any recommended product, but patients with prior allergic reactions or myocarditis or pericarditis may require additional consideration.^7,9 Platform selection receives considerable attention, but timing and scheduling considerations are generally more important for most medically complex patients.⁸ Product selection should follow current CDC recommendations and clinical judgment.

Discuss Risks and Benefits With the Patient

Regardless of the patient’s circumstances or the vaccine product, pharmacists must describe potential adverse effects. Most reactions are mild and resolve quickly, such as injection site reactions, fatigue, headache, myalgia, fever/chills, joint pain, and nausea.¹⁰ Medically complex patients are usually less concerned about common adverse effects and are more likely to ask about the serious adverse effects.¹⁰

Myocarditis and pericarditis are rare and occur most often in adolescent and young adult males after mRNA vaccination.¹⁰ Most patients recover fully with appropriate treatment. Anaphylaxis is rare, typically occurring within minutes of vaccination.¹⁰

In patients who are pregnant or immunocompromised, reassurance and discussion of benefits are prudent.^4,8 Immunizers need to address patient concerns and misconceptions using evidence-based information.^4,8

Conclusion

COVID-19 vaccination recommendations continue to evolve, creating challenges for pharmacists who immunize medically complex adults. Although vaccine platform selection occasionally requires special consideration, timing and scheduling decisions are often more important. By obtaining a focused medical history, assessing vaccination history, identifying factors that may influence timing, and discussing risks and benefits with patients, pharmacists can help ensure that medically complex individuals receive appropriate protection while minimizing potential risks.

About the Author

Jeannette Y. Wick, MBA, RPh, FASCP, is director of the Office of Pharmacy Professional Development at the University of Connecticut School of Pharmacy in Storrs.

REFERENCES

1. 2025-2026 COVID-19 vaccination guidance. CDC. November 4, 2025. Accessed June 24, 2026. https://www.cdc.gov/covid/hcp/vaccine-considerations/routine-guidance.html?utm

2. Nellore A, Goepfert P, Tan CS, et al. IDSA 2025 guidelines on the use of vaccines for the prevention of seasonal COVID-19, influenza, and RSV infections in immunocompromised patients. Clin Infect Dis. Published online March 2, 2026. doi:10.1093/cid.ciag114

3. COVID-19 vaccination guidance for people who are immunocompromised. CDC. November 4, 2025. Accessed June 24, 2026. https://www.cdc.gov/covid/hcp/vaccine-considerations/immunocompromised.html

4. COVID-19 vaccines and pregnancy: conversation guide. American College of Obstetricians and Gynecologists. Updated August 2025. Accessed June 24, 2026. https://www.acog.org/programs/immunization-infectious-disease-public-health/tools-and-resources/covid-19-vaccines-and-pregnancy-conversation-guide-for-clinicians?utm

5. FDA approves required updated warning in labeling of mRNA COVID-19 vaccines regarding myocarditis and pericarditis following vaccination. News release. FDA. June 25, 2025. Accessed June 24, 2026. https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/fda-approves-required-updated-warning-labeling-mrna-covid-19-vaccines-regarding-myocarditis-and?utm6

6. Contraindications and precautions. CDC. November 4, 2025. Accessed June 24, 2026. https://www.cdc.gov/covid/hcp/vaccine-considerations/contraindications-precautions.html

7. Overview of COVID-19 vaccines and vaccination. CDC. November 4, 2025. Accessed June 24, 2026. https://www.cdc.gov/covid/hcp/vaccine-considerations/overview.html

8. IDSA 2025 guidelines on the use of vaccines for the prevention of seasonal COVID-19, influenza, and RSV infections in immunocompromised patients. Infectious Diseases Society of America. 2025. Accessed June 24, 2026. https://www.idsociety.org/globalassets/idsa/practice-guidelines/vaccine-gl/idsa-2025-guidelines-on-the-use-of-vaccines-for-the-prevention-of-seasonal-covid-19-influenza-and-rsv-infections-in-immunocompromised-patients-all-figures-and-tables.pdf?utm

9. Implementation guidance. CDC. November 4, 2025. Accessed June 24, 2026. https://www.cdc.gov/covid/hcp/vaccine-considerations/implementation.html#toc

10. Safety considerations for COVID-19 vaccines. CDC. November 4, 2025. Accessed June 24, 2026. https://www.cdc.gov/covid/hcp/vaccine-considerations/safety-considerations.html